Continuous dyeing process



March 1937- J. H. STRADLEY CONTINUOUS DYEING PROCESS Filed May 11, 1935INVENTOR. I: JHStrac/l? Patented Mar. 16, 1937 v UNITED STATESCONTINUOUS DYEING PROCESS James H. Stradley, Carneys Point, N. J.,assignor to E. I. du Pont de Nemours & Company, Wilv mington, Del., acorporation of Delaware Application May 11, 1935, Serial No. 21,017

2 Claims.

This invention relates to dyeing. More par-m ticularly the inventionrelates to a continuous method of dyeing. The invention has particularapplication to the dyeing of materials such as 5 yarn or fabric whichare in considerable lengths, and will be described in relation to thedyeing of a roll of cotton cloth. It is to be understood, however, thatthis particular description does not limit the invention beyond thescope of the appended claims.

There has been described in prior art a method which involves dyeing aroll of cotton coth with an azo dyestufi containing a free amino group,diazotizing the dyestufi" on the dyed cloth and coupling to it, whilestill on the fiber, an azo dyestufi coupling component. In that process,the first dyeing is carried out on a jigger, the essentials of whichinclude a tank, a roller at each side and one at the bottom of the tank.The cloth is wound on one roller, passed under the roller in the tank,and attached to the other roller; the tank is filled with dye solution,the cloth is drawn back and forth through the dye bath, the temperatureis raised almost to boiling, and the material is given four to sixadditional passages through the solution. When the desired shade hasbeen obtained the tank is drained, filled" with cold water, and thematerial rinsed by repeated passages through the water.

0 The rinsing bath is drained off, the tank is filled with a diazotizingbath heated to 60-70" F., the cloth is twice passed through the bath,the machine is drained and filled with fresh water, and the cloth isagain rinsed. The tank is once more drained, is filled with a couplingbath containing an azo dyestufi' coupling component, and the cloth isgiven two passages at 60-70 F. to form the final dye. The tank isemptied, filled with fresh water, the material is passed through untilit is ing of the undyed fiber is carried out by a single passage throughthe dyestuif solution.

Attempts have heretofore been made to dye by,

this method continuously: A number of tanks have been alined and thecloth has been passed through them in succession. Thus, in one meth- 0dthe original 'dyestuff was applied by padding,

and the diazotization and development wereaccomplished by passing thecloth through the alined tanks containing a concentrated diazotizingbath heated to. -70 F a rinsing bath, a concentrated developer bath, andas many rinses 5 and soapings as was advantageous. The cloth was driedby passage over heated rollers.

The value of the method described in the preceding paragraph was limitedbecause it was necessary for the cloth to remain in contact with 10 thediazotizing and developing agents for the period ,of time requiredforflthe slowest bath to operate, which in almost all cases provedexcessive; because the use of very concentrated diazotizing anddeveloping baths reduced the time of 15 immersion but entailed aninability to properly expose the material; and because the variation inthe rate of development of different dyes, and in the, shades obtained,limited the process to use with a very few dyestufis. j 20 Comparing themethods of the prior art, efiective diazotization was carried out in theintermittent method at low concentrations and low temperatures,temperatures above F. being undesirable. A typical bath contained per 25gallons of water 1.5 pounds of sodium nitrite, 2.5-3.0 pounds ofsulfuric acid (66 B.) or 1.87-2.25 pounds hydrochloric acid (20 B.), andthe temperature would be held at 60-70 The diazotization bath or thecontinuous process of 30 the prior art contained, per each 100 gallonsof water, 12 pounds of sodium nitrite, 9.4 pounds of sulfuric acid (66B.) or 21 pounds hydrochloric acid (20 B.), and was held at atemperature of 60'70 F. The coupling bath of the 5 intermittent priorart process contained (using beta naphthol in illustration), per 100gallons of water, 0.5 pounds of betanaphthol, and 0.5 pounds of causticsoda at a temperature of 60-70F. The continuous prior art processcontained per 100 0 gallons of water, 33.0 pounds of beta naphthol and16.5 pounds of caustic soda.

It is an object of the invention to dye materials by a continuousmethodwhich is equally applicable to all dyestuffs substantive to cottonand 45 regenerated cellulose and having a diazotizable ally throughdiazotizingsand' coupling baths main- -55 5 inafter described.

The process is illustrated in a preferred embodiment in the accompanyingdrawing, showing a diagrammatic representation of the dyeing of a rollof cloth, in which X is the roller holding the roll of cloth beforeapplying the process; Y

is the winding roller upon which the processed cloth may be collected; Rare rollers, all, some, or none of which may be driven. In the preferredform of the invention the rollers outside 15 the tanks will be drivenand those within the tank will be freely mounted. Driers, not shown, maybe located between tank G and roller Y.

On the roller X is wound dyed cloth of which the dyestuff has a freeamino group. The tank A contains a diazotizing bath. In the preferredform of the invention that bath contains per gallons of water 2 to 3pounds of sodium nitrite, 10 to 12 pounds of sulfuric acid (66 B.) or 8to 10 pounds of hydrochloric acid (20 B.), and will be maintained at atemperature of 140 F. The tank B contains running cold water, but insome instances it can be replaced by a shower bath. The rollers Rbetween tanks may, when it is advantageous, have complementary pressurerollers R to squeeze excess moisture out of the cloth; the moisture soexpelled may be caught in a trough T and conducted away from the processor back to, the tank A. After the cold-water rinse in tank B, the clothdyed with the diazotized dyestuif is drawn into tank C which contains adeveloping bath. The developer selected by the dyer will depend on thecolor and shade desired in the final dye. An exemplary bath contained '1to 2 pounds of beta naphthol, and 1 /2 to 2 pounds of caustic soda per100 gallons of water, heated at about 140 F. The other azo dyestuficoupling components may be used in place of the beta naphthol. Forinstance, 1 to 2 pounds of 1-phenyl-3-methyl-pyrazolone, or 1 to 1pounds of 2:4-diamino-toluene produce similar results when used with 1to 1 pounds of caustic soda. Other coupling components whose use iscontemplated include: hydroxy aryls such as beta napththol andresorcinol; amino aryls such as 2:4-diamino-toluene, 1:S-diamino-benzene, and ethyl-beta-naphthylamine; hydroxy arylcarboxylic acids such as beta-hydroxy-naphthoic acid and its amides;pyrazolones such as methylphenyl pyrazolone, amino-aryl-pyrazolone, andaryl-carboXy-pyrazolone; and aceto-acet arylids such asaceto-acet-anilide. Sulfonic acid derivatives of the above classes canbe used, but in many cases they tend to solubilize the dye to anundesirable extent. This listing of coupling components is exemplary ofclasses not an exhaustive list of compounds.

Passing from tank C, the cloth with the newlydeveloped dyestufi isrinsed in cold water in tank D, soaped at -140 F. in box E whichcontains about three "pounds of soap to each 100 gallons of water,rinsed in warm water (about 120 F.) in box F, and in cold water(preferably running) in box G. The dyed and washed cloth may, ifdesired, be dried before winding on roller Y.

The temperature of F. is not an operative upper limit, satisfactoryresults being obtainable 75 upwardly thereof, but it is a temperature atwhich excellent efiiciency is obtained and above which the evolution ofgases is excessive.

An advantage of the invention is a continuous process of dyeing usefulwith substantially all dyestuff substantive to cotton and regeneratedcellulose and capable of diazotization and development on the fiber.This advantage is illustrated by reference to the following colors,identified by the Color Index Number, which could not be successfullyused by the old continuous process, but produce entirely satisfactoryresults when applied by my process.

CI-297 Diazotized and developed with beta naphthol CI-317 Diazotized anddeveloped with beta naphthol 01-322 Diazotized and developed with betanaphthol CI-323 Diazotized and developed with 2:4-diamino-toluene 01-324Diazotized and developed with l-phenyl- B-methyl-pyrazolone CI-324aDiazotized and developed with beta naphthol CI-339 Diazotized anddeveloped with beta naphthol CI-401 Diazotized and developed with2:4-diamino-toluene CI-552 Diazotized and developed with2:4-diamino-toluene CI-625 Diazotized and developed with betanaphtholCI-812 Diazotized and developed with naphthol Another advantage of theinvention is in the saving of time and labor in dyeing. In the jiggermethod three to five hours were required to complete the dyeing process.The continuous process of the prior art, when used with those few colorswhich could be successfully applied, acted in about three minutes perbath. My invention operates on cotton or regenerated cellulose with anydyestuff of the class described and reduces the time to about tenseconds per bath. Another advantage of my process is that theconcentration of 'diazotizing and developing baths is about equal to theprior intermittent process and far lower than those of prior continuousprocesses.

The use of alkaline coupling baths in the examples is not a limitationto baths of that type. The coupling bath will be made alkaline, neutral,or acid in accordance with the dictates of good practice relating toeach particular coupling component.

The fastness to washing, and discharge properties of the dyestufis whenproduced by my new continuous method are equal to those of the oldprolonged jigger process.

As many apparently widely diiferent embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that I do not limit myself to the specific embodimentsthereof except as defined in the appended claims.

I claim:

1. A continuous method of dyeing which comprises passing a material ofthe class consisting of cellulose and regenerated cellulose dyed with anazo dyestuif substantive to cotton or regenerated cellulose having adiazotizable amino group through a diazotizing bath heated to about 140F. and a coupling bath containing an azo dyestuff coupling component,the material being betaimmersed in said diazotization bath for a periodof time not greater than about ten seconds.

2. A continuous method of dyeing which comprises passing a material ofthe class consisting of cellulose and regenerated cellulose dyed with anazo dyestufi substantive to cotton or regenerated cellulose and having adiazotizable amino group, through a diazotizing bath heated to about 140F., and a coupling bath containing an azo dyestufi coupling componentselected from the group consisting of beta naphthol, 2:4-dlaminotolueneand 1-phenyl-3-methyl-pyrazolone, the material being immersed in saiddiazotization bath for a period of time not greater than about tenseconds.

- JAMES H. STRADLEY,

